The Empirical Analysis of Cigarette Tax Avoidance and Illicit Trade in Vietnam, 1998-2010

Illicit trade carries the potential to magnify existing tobacco-related health care costs through increased availability of untaxed and inexpensive cigarettes. What is known with respect to the magnitude of illicit trade for Vietnam is produced primarily by the industry, and methodologies are typically opaque. Independent assessment of the illicit cigarette trade in Vietnam is vital to tobacco control policy. This paper measures the magnitude of illicit cigarette trade for Vietnam between 1998 and 2010 using two methods, discrepancies between legitimate domestic cigarette sales and domestic tobacco consumption estimated from surveys, and trade discrepancies as recorded by Vietnam and trade partners. The results indicate that Vietnam likely experienced net smuggling in during the period studied. With the inclusion of adjustments for survey respondent under-reporting, inward illicit trade likely occurred in three of the four years for which surveys were available. Discrepancies in trade records indicate that the value of smuggled cigarettes into Vietnam ranges from $100 million to $300 million between 2000 and 2010 and that these cigarettes primarily originate in Singapore, Hong Kong, Macao, Malaysia, and Australia. Notable differences in trends over time exist between the two methods, but by comparison, the industry estimates consistently place the magnitude of illicit trade at the upper bounds of what this study shows. The unavailability of annual, survey-based estimates of consumption may obscure the true, annual trend over time. Second, as surveys changed over time, estimates relying on them may be inconsistent with one another. Finally, these two methods measure different components of illicit trade, specifically consumption of illicit cigarettes regardless of origin and smuggling of cigarettes into a particular market. However, absent a gold standard, comparisons of different approaches to illicit trade measurement serve efforts to refine and improve measurement approaches and estimates.     

Ammonium photo-production by heterocytous cyanobacteria: potentials and constraints

Over the last decades, production of microalgae and cyanobacteria has been developed for several applications, including novel foods, cosmetic ingredients and more recently biofuel. The sustainability of these promising developments can be hindered by some constraints, such as water and nutrient footprints. This review surveys data on N₂-fixing cyanobacteria for biomass production and ways to induce and improve the excretion of ammonium within cultures under aerobic conditions. The nitrogenase complex is oxygen sensitive. Nevertheless, nitrogen fixation occurs under oxic conditions due to cyanobacteria-specific characteristics. For instance, in some cyanobacteria, the vegetative cell differentiation in heterocyts provides a well-adapted anaerobic microenvironment for nitrogenase protection. Therefore, cell cultures of oxygenic cyanobacteria have been grown in laboratory and pilot photobioreactors (Dasgupta et al., 2010; Fontes et al., 1987; Moreno et al., 2003; Nayak & Das, 2013). Biomass production under diazotrophic conditions has been shown to be controlled by environmental factors such as light intensity, temperature, aeration rate, and inorganic carbon concentration, also, more specifically, by the concentration of dissolved oxygen in the culture medium. Currently, there is little information regarding the production of extracellular ammonium by heterocytous cyanobacteria. This review compares the available data on maximum ammonium concentrations and analyses the specific rate production in cultures grown as free or immobilized filamentous cyanobacteria. Extracellular production of ammonium could be coupled, as suggested by recent research on non-diazotrophic cyanobacteria, to that of other high value metabolites. There is little information available regarding the possibility for using diazotrophic cyanobacteria as cellular factories may be in regard of the constraints due to nitrogen fixation.     

Oxysterols: biological activities and physicochemical studies.

To improve the understanding of the various biological activities of oxysterols (oxygenated derivatives of cholesterol), studies of their physicochemical properties have been undertaken. Oxysterols modify membrane dynamic properties which consequently trigger several biological effects. Despite the presence of at least one oxygenated group in addition to the C3 beta-hydroxyl, oxysterols insert perfectly into the lipidic bilayer of the membrane inducing a condensing effect similar to, but less potent than, that of cholesterol. In biological membranes oxysterols probably interact with membrane components as they are not easily exchanged after their incorporation into the cell membrane. These lipid-protein interactions are probably crucial for the expression of the biological activities of the oxysterols.     

A rat gene encoding heart 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase.

There are at least 3 isozymes of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase, a bifunctional enzyme which catalyzes the synthesis and degradation of fructose 2,6-bisphosphate. A 22-kb rat gene that encodes the heart isozyme has been identified and compared with the 55-kb rat gene encoding the liver and muscle isozymes which had been described earlier. Although these 2 genes include 12 successive similar exons, they contain dissimilar exons at both ends, consistent with the occurrence of different regulatory domains at the N- and C-termini in the 3 isozymes.     

Studies of the oxysterol inhibition of tumor cell growth

The oxysterols 3 beta-hydroxy-5 alpha-cholest-8-en-11-one, 3 beta-hydroxy-5 alpha-cholest-8-en-7-one, 3 beta-hydroxy-5 alpha-cholest-8(14)-en-7-one, 3 beta-hydroxy-4,4'-dimethylcholest-5-ene-7 one, 4,4'-dimethylcholest-5-ene-3 beta, 7 alpha-diol, 4,4'-dimethylcholest-5-ene-3 beta, 7 beta-diol, lanost-8-ene-3 beta, 25-diol, 25-hydroxylanost-8-en-3-one, 9 alpha, 11 alpha-epoxy-5 alpha-cholest-7-en-3 beta-ol, 3 beta-hydroxycholest-5 alpha-en-22-one, and 3 beta-hydroxycholest-5-en-22-one oxime were evaluated with respect to their ability to inhibit cell growth. All of the sterols were found to possess cytotoxicity when incubated with hepatoma (HTC) and lymphoma (RDM-4) cells in culture at 10-30 microM concentrations.     

Inactivation of liver 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase by o-phthalaldehyde.

The two activities of chicken liver 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase were inactivated by o-phthalaldehyde. Absorbance and fluorescence spectra of the modified enzyme were consistent with the formation of an isoindole derivative (1 mol/mol of enzyme subunit). The inactivation of 6-phosphofructo-2-kinase by o-phthalaldehyde was faster than the inactivation of fructose-2,6-bisphosphatase, which was concomitant with the increase in fluorescence. The substrates of 6-phosphofructo-2-kinase did not protect the kinase against inactivation, whereas fructose-2,6-bisphosphate fully protected against o-phthalaldehyde-induced inactivation of the bisphosphatase. Addition of dithiothreitol prevented both the increase in fluorescence and the inactivation of fructose-2,6-bisphosphatase, but not that of 6-phosphofructo-2-kinase. It is proposed that o-phthalaldehyde forms two different inhibitory adducts: a non-fluorescent adduct in the kinase domain and a fluorescent isoindole derivative in the bisphosphatase domain. A lysine and a cysteine residue could be involved in fructose-2,6-bisphosphate binding in the bisphosphatase domain of the protein.     

Cloning and expression in Escherichia coli of a rat hepatoma cell cDNA coding for 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase.

In liver, the 470-residue bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2) catalyses the synthesis and degradation of fructose 2,6-bisphosphate, a potent stimulator of glycolysis. In rat hepatoma (HTC) cells, this enzyme has kinetic, antigenic, and regulatory properties, such as insensitivity to cyclic AMP-dependent protein kinase and lack of associated FBPase-2 activity, that differ from those in liver. To compare the sequence of the HTC enzyme with that of the liver enzyme, we have cloned the corresponding fully-coding cDNA from HTC cells. This cDNA predicts a protein of 448 residues in which the first 32 residues of liver PFK-2/FBPase-2 including the cyclic AMP target sequence have been replaced by a unique N-terminal decapeptide. The rest of the protein is identical with the liver enzyme. An N-terminally truncated recombinant peptide of 380 residues containing the PFK-2 and FBPase-2 domains was expressed in Escherichia coli as a beta-galactosidase fusion protein. It was recognized by anti-PFK-2 antibodies but its enzymic activities were barely detectable. In contrast, a cDNA fully-coding for the HTC enzyme could be expressed in E. coli as a beta-galactosidase-free peptide that exhibited both PFK-2 and FBPase-2 activities. This peptide had those PFK-2 kinetic properties of the HTC enzyme that differ from the liver enzyme. These data, together with immunoblot experiments, suggest that the lack of associated FBPase-2 activity in HTC cells results from a post-translational modification of the enzyme rather than from the difference in amino acid sequence. As well as this peculiar type of PFK-2/FBPase-2 mRNA, HTC cells also contained low concentrations of the liver-type mRNA. Unlike in liver, neither mRNA was induced by dexamethasone in these cells.     

Effect of Growth Conditions and Trehalose Content on Cryotolerance of Bakers' Yeast in Frozen Doughs

The cryotolerance in frozen doughs and in water suspensions of bakers' yeast (Saccharomyces cerevisiae) previously grown under various industrial conditions was evaluated on a laboratory scale. Fed-batch cultures were very superior to batch cultures, and strong aeration enhanced cryoresistance in both cases for freezing rates of 1 to 56°C min⁻¹. Loss of cell viability in frozen dough or water was related to the duration of the dissolved-oxygen deficit during fed-batch growth. Strongly aerobic fed-batch cultures grown at a reduced average specific rate (μ = 0.088 h⁻¹ compared with 0.117 h⁻¹) also showed greater trehalose synthesis and improved frozen-dough stability. Insufficient aeration (dissolved-oxygen deficit) and lower growth temperature (20°C instead of 30°C) decreased both fed-batch-grown yeast cryoresistance and trehalose content. Although trehalose had a cryoprotective effect in S. cerevisiae, its effect was neutralized by even a momentary lack of excess dissolved oxygen in the fed-batch growth medium.